This invention relates to reflective highway markers used to mark highway lanes for guidance, cautionary and safety purposes. Conventional reflective highway markers may be classified in two general categories: (a) the group of reflective highway markers which are embedded within the highway pavement, and (b) the group of reflective highway markers which at least in part extend above the pavement surface. The latter group provides superior reflectivity under optimum conditions. However this group is vulnerable to snow plows and to the general destructive consequences of repeated contact with motor vehicle tires. The former category of reflective highway markers is protected against damage from snow plows and contact with motor vehicle tires but this category provides inadequate reflectivity at normally encountered approach distances.
An illustration of the category of embedded reflective highway markers is U.S. Pat. No. 4,136,990 issued to Alan W. Morgan on Jan. 30, 1979. While this patent discloses a highway marker which is mounted within a recess formed in a highway pavement, it is evident from the angle of the reflective surfaces, and from the clearance in advance of the reflective surfaces that the highway marker would not function when oncoming vehicles are at substantial approach distances, e.g., 200 yards from the highway marker. As stated in the specification of U.S. Pat. No. 4,136,990, column 2, lines 42-47 the reflective surfaces are positioned at an angle in the range of 30 to 60 degrees, presumably from the vertical. As stated in column 3 of the specification, lines 2-4, the individual marker is 4 inches square and it is mounted in a recess which is only 3/4 of an inch deep (column 2, lines 61-64). It is evident that a marker made in accordance with this patent would be functionally effective within a relatively short range, and certainly nowhere near the 200 yard range above mentioned.